Horizontal gene transfer in the mitochondria of holoparasitic plants of the family Balanophoraceae

SANCHEZ PUERTA, MV

Malmo

Congreso; ICPMB. 12th International Conference for Plant Mitochondrial Biology.; 2022

Parasitic plants are characterized by their ability to feed directly on other plants, invading the roots or stems of their hosts through specialized structures called haustoria. The haustoria connect the vascular tissue of the parasitic plant with that of the host plant and allow the transfer of nutrients, water, and even nucleic acids. Parasitic plants account for almost 1% of flowering plants and originated independently in 12 lineages of angiosperms from free-living ancestors. An interesting consequence of the intimate host-parasite connection is horizontal gene transfer (HGT). The HGT process refers to the movement of genetic information between different species. Most reported cases of plant-to-plant HGT involve the mitochondria, to a lesser extent the nucleus, with a notable absence in the chloroplasts. Holoparasitic plants of the family Balanophoraceae (Santalales) represent an excellent system to examine the role of HGT, the expression of foreign genes, and its effect on the nucleo-cytoplasmic compatibility. Extraordinary levels of horizontal transfers from their hosts were identified in the mitochondrial genomes of Lophophytum spp. and Ombrophytum subterraneum. Even though most foreign mitochondrial genes become pseudogenes, we uncovered the unprecedented functional replacement of 75% of the native mitochondrial protein-coding genes in L. mirabile. Both ancestral and recent HGT events took place during the evolution of the Balanophoraceae. Finally, proposed recombination mechanisms for the integration of foreign DNA are presented.